1. Field of the Invention
The invention relates to a plasma processing apparatus or a plasma processing method and, more particularly, to a plasma processing apparatus or a plasma processing method in which a film arranged on the surface of a sample as a processing target is processed by realizing conditions of different processes.
2. Description of the Related Art
In the case of using a plasma processing apparatus as mentioned above in order to manufacture a semiconductor apparatus such as a semiconductor device or the like, it is necessary that a film arranged on the surface of a substrate-like sample such as a semiconductor wafer having a disk shape of a processing target is processed at high precision. In recent years, in order to improve an integration degree of the semiconductor apparatus, processing conditions such as temperature distribution and the like regarding a radial direction and a circumferential direction of the sample are adjusted so as to have desired values. Particularly, in an etching process for processing the film on the surface of the semiconductor wafer by using a plasma formed in a processing room in a vacuum chamber in which the semiconductor wafer is arranged, the process is generally executed while a product formed in the plasma is deposited onto a side wall of a groove or hole structure formed by etching. Since a deposition degree of such a deposit is largely influenced by a temperature, a value of the temperature of the surface of the sample which is being processed and its distribution are significant conditions upon realizing the high precision process. Therefore, in order to precisely adjust the temperature of the surface of the sample during the processing of the sample, there has been known such an apparatus in the related art that a passage of a coolant is arranged in a sample stage (holder) where the sample is put on its upper surface or a gas having heat transfer performance is supplied into a space between the sample stage and the sample, and a pressure of the gas is properly adjusted, thereby maintaining the sample temperature within a range of proper values.
In recent years, a microfabrication of a device structure is being progressed in association with an increase in integration degree of a semiconductor integrated circuit and, in many cases, the device constructed by a single layer film in the related art is formed as a laminate layer in a plurality of film kinds in accordance with a requirement for improvement of characteristics. For example, in wirings, as for a wiring material constructed by an aluminum single layer in the related, such a technique that an upper layer film and a lower layer film of the wiring material are made of, for example, titanium nitride and laminated for the purpose of satisfying requirements for improvement of reliability and high exposure resolution is widely used. Further, in recent years, the laminate structure is also used for a gate electrode in order to satisfy requirements for a high speed of a transistor and a low electric power consumption. In order to realize such a fine structure of the semiconductor device, such a technique that processes are continuously executed to a structure of a plurality of films laminated on the surface of the semiconductor wafer while making processing conditions different according to each film or that one film is continuously processed under a plurality of different conditions is used. According to such processes, in order to increase the number of samples to be processed per unit time, it is desirable to change the processing conditions while keeping the samples on the sample stage in the processing room. However, if a long time is expended for such a change in processing conditions as mentioned above, processing efficiency (throughput) deteriorates.
According to the technique for circulating the coolant in the passage arranged in the sample stage, it takes a longer time to change the temperature of the sample stage than that in the case of changing a pressure of the gas having the heat transfer performance because of a magnitude of a heat capacity of the coolant. Therefore, if it is intended to change the temperature value and its distribution for a period of time between the foregoing processes which are continuously executed, the throughput deteriorates. According to the technique for changing the pressure of the heat transfer performance gas (for example, He or the like), although the pressure change and a change in heat transfer coefficient between the sample and the sample stage due to the pressure change can be realized in a relatively short time, the temperature change of the sample due to the change in heat transfer coefficient can be performed only in the case where the heat from the plasma formed in the space over the sample stage in the processing room is supplied to the sample and transferred to the sample stage, that is, only in the case where the heat transfer through the sample has occurred between the plasma and the sample stage. There are consequently the following problems the above technique cannot be applied to such a process that the plasma is extinguished for a period of time of the change in processing conditions mentioned above. Characteristics such as a speed and the like of the processes at the initial stage where the plasma was formed differ from characteristics of the processes in a state where the plasma is stabilized after that, so that the processing precision is deteriorated.
To solve such problems, there is such a technique that a heating device such as a heater or the like is arranged in the sample stage and the value of the sample temperature or its distribution is adjusted by heating the sample stage by the heater (further, a cooling process by a flow of the coolant in the sample stage may be also used). As such a related art, the method disclosed in JP-T-2004-533718 (published Japanese translation of a PCT appln.) corresponding to U.S. Pat. No. 7,274,004 etc. has been known. According to such a related art, the heater is built in an electrode made of a conductive material (metal) in the sample stage and an electric power which is supplied to the heater is controlled on the basis of an output value detected by a temperature sensor embedded near the heater, so that temperature distribution in the sample stage is adjusted, thereby indirectly adjusting a wafer temperature so as to obtain desired value and distribution.